Agricultural heating devices

ABSTRACT

A natural-draft space heater, having a conventional fuel jet which produces a hollow fuel cone when fed with pressurized fuel oil or compressed gas. The jet is spaced below a base plate having a central hole therethrough and is disposed centrally within the hole with the axis of the fuel cone perpendicular to the base plate. The heater also comprises an upright chimney, having a preferred height of 24 inches, which is disposed on the base plate, and a dispersal plate, of the same size as the central hole, spaced thereabove, aligned therewith, and spaced therefrom so that it intercepts the tulip-shaped hollow cone to produce a wet ring (before ignition) about 1/8 inch to 1/16 inch in thickness adjacent to its circular edge. The preferred diameter of the dispersal plate is about 3 1/2 inches, and the preferred interplate spacing is about 3 inches. The intercepted cone is reflected outwardly and downwardly and may be ignited with a 6-volt ignition device attached to the base plate. After ignition, the deflected flame extends radially from the circular edge but does not exist between the orifice and the circular edge. With fuel oil at 70 psig, the flame is about 4 inches long; with pressurized gas at 0.5 psig, the flame is about 3 inches long, 0.5 gallons per hour of each fuel being burned at these conditions. Tested particulate emissions were 0.2 grams per minute for diesel fuel and 0.005 grams per minute for propane gas at these conditions.

United States Patent [1 91 Lee [451 Apr. 9, 1974 AGRICULTURAL HEATINGDEVICES [76] Inventor: Curtis John Lee, Po. Box 127,

Wimauma, Fla.

[22] Filed: Nov. 27, 1972 [21] Appl. No.: 309,921

Related US. Application Data [63] Continuation-impart of Ser. Nov143,161, May [3.

l97l, abandoned.

Primary Examiner-William E. Wayner Assistant Examiner-William E.Tapolcai,..lr. Attorney, Agent, or FirmLowe, King & Price 57 4 ABSTRACTA natural-draft space heater, having a conventional fuel jet whichproduces a hollow fuel cone when fed with pressurized fuel oil orcompressed gas. The jet is spaced below a base plate having a centralhole therethrough and is disposed centrally within the hole with theaxis of the fuel cone perpendicular to the base plate. The heater alsocomprises an upright chimney, having a preferred height of 24 inches,which is disposed on the base plate, and a dispersal plate. of the samesize as the central hole, spaced thereabove, aligned therewith, andspaced therefrom so that it intercepts the tulip-shaped hollow cone toproduce a wet ring (before ignition) about Va inch to ill 6 inch inthickness adjacent to its circular edge. The preferred diameter of thedispersal plate is about 3% inches, and the preferred interplate spacingis about 3 inches. The intercepted cone is reflected outwardly anddownwardly and may be ignited with a 6-volt ignition device attached tothe base plate. After ignition, the deflected flame extends radiallyfrom the circular edge but does not exist between the orifice and thecircular edge. With fuel oil at 70 psig, the flame is about 4 incheslong; with pressurized gas at 0.5 psig, the flame is about 3 incheslong, 0.5 gallons per hour of each fuel being burned at theseconditions. Tested particulate emissions were 0.2 grams per minute fordiesel fuel and 0.005 grams per minute for propane gas at theseconditions.

10 Claims, 12 Drawing Figures 1 AGRICULTURAL HEATING DEVICESCROSS-REFERENCES TO RELATED APPLICATIONS The present application is acontinuation-in-part of co-pending application Ser. No. 143,161, filedMay 13, 1971, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to fuel-burning devices and particularly relates toradiation-convection heaters. It especially relates to space heaters ofthe natural-draft or blowerless type which operate on pressurized fuelsand are intended forraisingthe temperature of the air over large areasduring temporary frost conditions.

Fuel-burning devices which occupy a minimum of space are useful instoves, ovens, heaters, and the like, and space heaters havingversatility, simplicity, and

economy of fuel consumption are widely useful, particoils, rubber, andthe like), and in recent years bymech'anical delivery of combustibles tothe area of need for burning in specialized space heating deviceswhichgenerally produce considerable visible pollution of the environment.

2. Review of the'Prior Art Many ingenious devices have been developedfor burning of such mechanically delivered combustibles. For example,U.S. Pat. No. 3,409,000 of Brader et al. describes a heater having aflame-constraining heatradiant shroud or chimney which is closed at bothends exceptfor central holes therein, a specially "designed oil-mistgenerating nozzle being disposed inthe lower hole and numerous small airinlet openings being in the side walls of the shroud so that the entirevolume of the shroud is filled with flames 'upon ignition of the oilmist.

U.S. Pat. No. 3,502,066 of l-lurd also describes a blowerlessnatural-draft heater which uses a vertically disposed cylindricalchimney having a closed bottom through the inlet hole and against ahorizontally disposed baffle disposed thereabove.

Although these devices have greatly facilitated base heating ofindustrial construction areas, orchards, citrus groves, truck croplands,and the like, they are subject to numerous disadvantages. One widelyused heater, for example, has a small baffle plate over and around whichthe fuel squirts so that it seems to be about 50 percent effective.Anothegpopular sp ice fi'eatfisifig, heavy, and expensive, burns 2.5gallons per hour of fuel at 200 psig, and produces a big flame whichseems to climb high in the sky yet requires 35 heaters per acre toprotect a central Florida citrus grove where two frosts per year can beexpected. Using another space heater, 60 heaters per acre are 'requiredin the same area.

Furthermore, most commonly used space heaters of the pressurized-fueltype require a minimum of 125 psig fuel pressure and consequently incurhigher piping costs because polyvinyl chloride pipe comes in aninexpensive weight for 0-100 psig and an expensive weight for over psig.This heavier weight pipe is also harder to handle, more difficult toseal against leaks, and onerous to move to other locations after buryingin the ground. A S-horsepower motor is also necessary to supply the samequantity of oil at psig fuel pressure as a 3-horsepower motor suppliesat 70 psig through pipe of equal size. Each heater in the prior artadditionally requires a stainless-steel clamp for every connection ofPVC pipe to PVC tubing and of PVC tubing to a heater fuel inlet pipe.

When a citrus grove must be protected against an incoming cold wave,space heaters are usually concentrated along the first two rows of treeson the windward side of the grove, and others are dispersed therebehind.Attendants range the grove during the night, checking for heaters thathave gone out and watching for overturned heaters that could causefires.

The large, heavy, natural-draft space heaters now available additionallyhave no storage means for minimizing storage space requirements duringthe summer months. Although many have means for flattening or stackingof cylindrical shapes, none are satisfactory because of metal-to-metalcontact under pressure, creating corrosion and freezing. Consequently,they must be left in place during the entire year while exposed to theweather or' must be gathered and stored in a relatively large storagefacility.

As a further disadvantage of present-day naturaldraft heaters, theirlarge flames and high fuel consumption create an ever-present firehazard whenever high winds overturn a heater or a delay occurs inigniting the heaters after admitting the high-pressure fuels thereto.The high fuel pressure, large flames, and heated structure prevent theflame from being extinguished if the heater is knocked over, and becauseof the high fuel pressure and large output of fuel, large quantities ofunburned fuel can quickly accumulate on the ground before ignition ofthe fuel. A fire under such conditions among the dry winter cover of anorchard or citrus grove can result in losing many of the bearing treesand must be avoided at all costs.

An increasingly important handicap to natural-draft heaters now on themarket, in view of the recent ecological furor, is the quantity ofvisible smoke and flame that'is emitted from each heater because ofincomplete combustion therein. A grove that is located in a state havingstrict enforcement of pollution regulations consequently must attempt touse a minimum of fuel and obtain complete combustion thereof.

Yet the fruit has its own imperative demands. For example, orangesfreeze at 27 F. if exposed for a sufficiently long time. At 25 F., 6hours is enough for the cold to destroy the fruit, but at 26 F., thesame amount of time is enough for thecold to destroy bark of bearingtrees; obviously loss of the trees is far more serious. Regardless ofthe pollution which may result, therefore, the manager of a citrus grovemust somehow provide at least a minimum of an 8 F. rise in temperatureif the cold wave temperature is expected to drop to 19 F.

These disadvantages could clearly be overcome if extremely efficientburning of relatively low-pressure fuel could be provided in a simple,inexpensive, natural-draft heater having a storage-space economizingmeans and producing no outwardly visible flame or signiflcantatmospheric pollution.

SUMMARY OF THE INVENTION The object of this invention is to provide anaturaldraft fuel burning means that efficiently consumes relativelylow-pressure fuel and produces a small, radially attenuated flame.

An accompanying object is to provide a natural-draft fuel having meansand method for efficient space heating while creating negligibleparticulate emission.

Another object is to provide a natural-draft space heater which utilizesfuels at pressures below 100 psig.

An additional object is to provide a natural-draft space heater whichefficiently consumes relatively small quantities of pressurized fuelsand emits negligible quantities of particulate matter.

A further object is to provide a natural-draft space heater which lacksfire-starting characteristics because of its small, radially emittedflames, relatively cool heater structure, and relatively small fuelconsumption.

Still another object is to provide a natural-draft space heater having astorage-space economizing means.

In satisfaction of these objects and in accordance with the spirit ofthis invention, a natural-draft fuel burning means is provided hereinwhich includes a base plate having a central hole therethrough; adispersal plate of the same size and shape as the central hole which isaligned with and spaced therefrom; a fuel jet to receive pressurizedfuel and emit a hollow fuel cone which is coaxially aligned with thedispersal plate and the central hole and is so spaced from the dispersalplate that the hollow fuel cone, without contacting the base plate,strikes the dispersal plate in a ring which is adjacent to the circularedge thereof; and a barrier means which prevents suction air from makinga sidewise approach to the dispersal plate.

In further satisfaction of these objects, a natural-draftfuel burningspace heater is provided herein that includes this natural-draft fuelburning means and, as the barrier means thereof, an interchangeablyended, elongated chimney, which has means for disassembly andloose-fltting storage thereof as a storage-space economizing means thateliminates metallic corrosion.

This fuel burning means operates by radial attenuation of its flames sothat an open-buming flame is greatly shortened in length and attendantblack smoke emission is substantially eliminated. It does so byutilizing the concept of intercepting and deflecting a thin, hollow,vertically disposed, tulip-shaped fuel cone with a horizontally disposedbaffle plate so that the fuel creates a wet ring of pre-ignition fueladjacent to its circular edge and approximately l/l6 to inch inwardlythereof. The pre-ignition fuel is thereby dispersed and reflecteddownwardly toward a base plate and radially outwardly. The base plate isdisposed in parallel to the dispersal plate and perpendicularly to thefuel cone.

When deflected fuel is ignited, as can be done with a match orpreferably with an electrical igniter attached to the base plate,incoming air rushes diagonally upwardly toward the dispersal plate andradially outwardly toward its circular edge from a central hole in thebase plate which is of the same size and shape as the dispersal plateand is aligned therewith. On striking the plate-deflected and ignitedfuel while moving diagonally from the central hole to the circular edge,the air further disperses and mixes with the fuel, urges it radiallyoutwardly and away from the base plate, and causes the resulting flameto mix with an excess of air and become rapidly attenuated outwardly sothat complete combustion occurs before the flame is cooled below itsflash point by striking the heater structure.

No flame exists between the exit orifice of the fuel jet and thecircular edge of the dispersal plate.

By a design bringing 200 percent excess air while using a chimney soshort as to be essentially a sidebarrier means, the natural-draft spaceheater of this invention burns the available fuel very rapidly andcompletely while diluting the combustion gases so that only the chimneyportion of the heater structure becomes hot. The base of the heater iscool enough that it can be picked up with bare hands and held for anappreciable time while it is operating.

However, the size of the central hole and the length of the chimney areinter-related to a limited extent because, as in all natural-draftburning devices, the chimney acts to create a differential air pressurebetween the two sides of the base plate. Consequently, a sidewisebarrier to air movement toward the dispersal plate in combustion with apressurizing or vacuumizing means can be substituted for the chimney.

If knocked over, the fuel jet is readily disengaged from the base plate.The hollow fuel cone is then extinguished so that fuel is merely wastedwithout causing fire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective viewof the naturaldraft space heater of this invention.

FIG. 2 is a perspective view of the slide fastener used for the chimney.

FIG. 3 is an inset view of a slide fastener holding the backturned endsof sheet metal plate and thereby forming the chimney.

FIG. 4 is a perspective view of a plurality of metal sheets used for thechimney to illustrate stacking thereof.

FIG. 5 is a perspective view of a dispersal plate.

FIG. 6 is a persepctive view of the dispersal plate supporting means.

FIG. 7 is a perspective view of the fuel jet support means.

FIG. 8 is a perspective view of the igniter cover which is attached tothe base plate.

FIG. 9 is a perspective view of the igniter which flts within theigniter cover of FIG. 8.

FIG. 10 is a side elevation view of the igniter shown in FIG. 9.

FIG. 11 is an idealized partial sectional view of the dispersal plate,support means, base plate, fuel jet support means, fuel jet, and fuelinlet pipe for a liquid fuel, such as diesel fuel.

FIG. 12 is an idealized sectional view, similar to FIG. 11, which showsthe fuel jet and inlet pipe for a pressurized gas, such as propane.

DESCRIPTION OF THE PREFERRED EMBODIMENT The natural-draft space heatershown in the drawings comprises a base plate 4 having a central holewith sides 18 therein, a collar 3 attached thereto in annularrelationship to the central hole on the upper or flame side thereof andfunctioning as a chimney alignment means, a dispersal plate 5, aU-shaped fuel jet support means 9 which is attached to the base plate 4on the opposite side to the collar 3 (herein designated the fuel sidethereof), a fuel jet 7 which is attached to the fuel jet support means 9in coaxial alignment with the central hole and with the dispersal plate5, and a chimney 1 having a slide fastener 2 for formation of a cylinderfrom a bendable metal plate having backturned edges 15. The central holein the base plate 4 has sides 18. The dispersal plate 5 is disposed inparallel to the base plate 4, has a circular edge 19, and is annularlyaligned therewith.

Fuel jet support member 9 has a square hole therein through which eitherof the fuel jets 7b, 70 may be inserted. They are commercially availableunits. The fuel jet 7b is a fuel burner nozzle, identified as 0.75gallons-85 hollow cone for diesel fuel, which sprays 0.5 gallons ofatomized fuel per hour. The fuel jet 'Zc is a petroleum gas nozzle witha 1/64-inch orifice which sprays the vaporized gas obtained from 0.5gallons of compressed fuel per hour. Either fuel jet 7b, 7c is screwedinto the square, elbow-shaped nozzle adapter 8, as is clearly shown inFIGS. 11 and 12, which is a standard pipe elbow having a bastard threadfor adaptation to the fuel jet 7b, except that a thin support slot 21 ismilled into the square sides whereby the adapter 8, having the inletpipe screwed thereinto, can be fitted upwardly into the square hole upto the slot and then turned about A of a turn so that the inlet pipe 10is slipped into the base slot having edges 16in one of the downturnedcorners 17 of the base plate 4.

The slightest tipping movement of this space heater, such as overturningthereof by wind, causes rotational movement of the inlet pipe 10 out ofthe base slot so that the elbow adaptor 8 falls out of the square holein the fuel jet support member 9. When this happens, the flame isextinguished because in the open air the hollow gas cone cannot beignited and the oil cone will not bring any flame with it when detachedfrom the base while burning at 50 to 85 psig. The support slot 21 thusoperates as a safety release means.

The insulator 12 is a molded ceramic device having a pair of electrodes14 which are connected to a 6-volt source and a nichrome heating wire 13which becomes red hot when a 6-volt current is sent therethrough. Eventhough the nichrome heating wire 13 is beneath the cover 11, it easilyignites deflected fuel from the dispersal plate 5. However, afterignition and while air is rushing diagonally from the central holetoward the circular edge 19 and re-deflecting thedeflected fuel intoradially extending flames, the insulator 12 is not subject to directheat except for radiation which is intercepted by the top of the cover11. Consequently, the insulator l2 and nichrome heating wire 13 areuseable for long periods of time.

For natural-draft heating, the flame side of the base plate 4 isuppermost, and the fuel side thereof is lowermost. However, for use inovens, for example, wherein the fuel jet support means 9 can be a partof and be attached to a pressurized air supply duct, a plurality ofcentral holes and edge-aligned dispersal plates can be spaced in closeproximity and in upside-down position with a communal air barrier forpreventing sidewise access of air to the fuel being radially dispersedfrom the edges of each dispersal plate. Of course, if the air supplyduct is at atmospheric pressure, the necessary pressure differential canbe achieved by using a slight vacuum within the oven.

At 85 psig fuel pressure, when using a chimney l having a diameter of 12inches and a height of 24 inches, a dispersal plate 5 and a central holein the base plate 4 of about 3% inches in diameter, a spacing of about 3inches between the flame side of the base plate 4 and the dispersalplate 5, and a location of exit orifice of the fuel jet 7 at about 5 1inch below the fuel side of the base plate 4, the radially attenuatedflames begin to lick the sides of the chimney 1. If the wet preignitionring is not closely adjacent to the circular edge 19 of the dispersedplate 5, mixing is inadequate and the flame becomes smoky.

At psig for No. 2 diesel fuel, when using the same dimensions forcomponents and the same spacings, the flames are about 4 inches inlength; at 0.5 psig for pressurized propane gas, the flames are about 3inches in length. The exhaust gas is at a temperature of approximately1,450 E; yet the chimney 1 does not become red hot at any place.

The exit orifice can be disposed from about A inch to about inch belowthe fuel side of the dispersal plate 5. The chimney 1 can beapproximately 16 to 30 inches in length. The fuel jet 7 can be selectedto produce a cone varying from about to about Air flow tends to closethe cone to a tulip shape after 1 to 1% inches of flow. At 70 psig, thefuel consumption is 0.5 gallons per hour per heater and is sufficient toraise the temperature in a space thereabove by 18 P. if placed at aspacing of 20 feet by 24 feet. Moreover, at pressures of 50-85 psig,this heater does not require a tubing clamp to secure flexible tubing tothe inlet pipe 10, nor is a clamp required to attach such tubing to thepipe risers at ground level which are connected to the underground pipesystem.

When this heater is operated at a fuel pressure of 50 psig, it will notraise the temperature of a space thereabove by 18 F., when scattered at90 heaters per acre, but by a considerably lesser temperature. Thus itfunctions as a frost protector rather than a freeze protector.

When the space heater of this invention is operated at 50-85 psig fuelpressure, the flames do not contact the side of the chimney 1. Withinthis range of fuel pressure, the flame burns cleanly. However, the flamewill start to smoke at inlet pressures above about psig and also atinlet pressure below about 50 psig. Moreover, the fuel will not igniteproperly at fuel inlet pressures below 50 psig.

When the downturned corners 17 of the base plate 4 are thrust into soil,the elbow adaptor 8 is generally spaced from the underlying ground-andthere is abuncifically, the fuel side of the base plate 4 should beabout 2% inches above the ground, but the support member 9 will maintainsufficient distance to operate the heater under unusual circumstances asa spacer means.

In a citrus grove having an average concentration of 30 of thesenatural-draft space heaters per acre, the surrounding air is readilyraised by 8 F. in temperature when 0.5 gal/hr of liquid fuel is consumedat a dieseloil fuel pressure of 70 psig or a gas pressure of 0.5 psig.Moreover, because the radiant temperatures are relatively low, radiantheat seems to move horizontally, about 18 inches above the ground, andapparently climbs upwardly along the trunks of nearby citrus trees intothe canopy of branches and leaves where all too often cold air seems tobecome entrapped and cause damage to or loss of the valuable trees whena grove is heated by relatively high-temperature space heaters that sendflames roaring high into the air.

In an outdoor test by an independent testing agency in Florida, it wasnoted that the plume was barely visible and would waver and waft out ofthe chimney because of its low velocity and that combustion occurredwithin the bottom few inches of the chimney. Test methods followed theFlorida Standard Sampling Techniques published by the Department ofPollution Control in January, 1971. Flue gas volumes were measureddirectly, using a pitot tube and a low-range draft gage, plusthermoanemometers, and indirectly using Orsat measurements with percentexcess air related to theoretical air.

The result of the two tests were averaged as 0.2 grams per minute withstandard (No. 2) diesel fuel and 0.005 grams per minute with propanegas. Calculations from Orsat analyses gave 197 percent excess air.

The method of this invention is clearly dependent upon the differentialin air pressure between the fuel side and the flame side of the baseplate 4. This fuel pressure can be created by pressurizing an enclosedspace on the fuel side of the base plate, by varying the height of thechimney, or by vacuumizing the space on the flame side of the base platewithout using a chimney except as a barrier for sidewise air movement.

The semi-flattening storage means of this invention comprises the slidefastener 2 and back-tumed edges of the chimney 1. When the slidefastener 2 is slideably removed from the edges 15, the chimney 1 springspartially into flattened shape. The storage method of this inventioncomprises: slideably removing the slide fastener 2 from nine chimneyunits; nesting the nine released chimneys; and inserting the nine nestedchimneys l and the nine slide fasteners 2 into a tenth chimney incylindrical condition for storage, whereby the natural springing of themetal during storage inhibits electrolysis effects and preventscorrosion.

As stated hereinbefore, devices constructed according to the principlesof this invention can operate without a closely disposed chimney. Forexample, a plurality of holes can be symmetrically located in a largebase plate having side barrier means and a pressurized space on the fuelside thereof or a vacuumized space on the flame side thereof. Such aplurality of heaters is useful in industrial furnaces, particularlybecause such heaters occupy very little transverse distance and, bysuitable control of differential air pressure, can be used with the baseplate in other than a horizontal position.

The beneficial effects of this invention are achieved by radialattenuation of the flames to obtain a greatly shortened flame and byadmixture of sufficient excess air that complete combustion is obtained,thereby moderating radiation effects, minimizing convective updrafts,and balancing bottom intake air with chimney discharge air so that aheating effect seems to flow in all directions from each heater, at aheight of about 18 inches above the ground, and climb into the foliagewhen intercepted by tree trunks.

This invention is also useful in cooking devices. For

example, a natural-draft space heater as described hereinbefore wasplaced in the bottom of a cast aluminum round stove having lava rock asa heating bed therein. After about 3 minutes of heating with this spaceheater, the rocks became hot enough that steaks thereabove began todrip. The heater was then turned off, and the heat of the stones cookedthe steaks uniformly and adequately.

This invention is additionally useful as a camp stove.

It can be modified by substituting a smaller fuel jet connected to asmall propane tank, and by using a proportionally smaller central holeand dispersal plate.

Because it will be readily apparent to those skilled in the art thatinnumerable variations, modifications, applications, and extensions ofthese embodiments and principles can be made without departing from thespirit and scope of the invention, what is herein defined as such scopeand is desired to be protected should be measured, and the inventionshould be limited, only by the following claims.

What is claimed is:

l. A natural-draft space heater, comprising:

A. a flat base plate having a flame side, a fuel side,

and a central hole therethrough;

B. a collar attached to said base plate in annular relationship to thesaid central hole and on the flame side of the base plate, and acting asa chimney alignment means;

C. a removable chimney, having open ends, which is disposed with one endperpendicularly adjacent to said flame side of the base plate andaligned by said collar and in surrounding relationship to said centralhole; said chimney being formed from a bendable metal plate havingbackwardly bent edges which are engaged by a C-shaped slide fastener,said chimney being interchangeable end for end and removable forstorage;

D. a substantially U-shaped fuel jet support means attached to said baseplate on the fuel side thereof;

E. a fuel jet, having a fuel inlet opening for pressurized fuels and anexit orifice capable of ejecting a hollow fuel cone, which is attachedto said fuel jet support means and disposed so that said fuel cone is incoaxial alignment with said central hole and does not contact said baseplate;

F. a dispersal plate support means; and

G. a circular dispersal plate attached to.said dispersal plate supportmeans which is aligned with and has substantially the same diameter asthe diameter of said central hole in said base plate and which isdisposed in parallel relation to and spaced from the flame side of thebase plate so that said dispersal plate intercepts said hollow fuel coneadjacent to said circular edge; whereby, in operation of said heater,the flame is attenuated outwardly j by the dispersal plate but without asubstantial portion of the flame contacting the side of the chimney, andwith such substantially complete combustion occurring in the lowerportion of the chimney that emission of combustion particulates issubstantially eliminated.

2. The natural-draft space heater of claim 1 wherein said dispersalplate is disposed in relation to said exit orifice so that said hollowfuel cone creates a ring of wet fuel adjacent to said circular edgebefore ignition thereof.

3. The natural-draft space heater of claim 2 wherein said ring of wetfuel extends 1/16 to A of an inch inwardly of said circular edge.

4. The natural-draft space heater of claim 3 wherein said exit orificeis spaced approximately one-fourth to 1% inch away from said fuel side.

5. The natural-draft space heater of claim 4 wherein said dispersalplate is spaced away from said flame side at a distance approximatelyequalling the diameter of said central hole.

6. The natural-draft space heater of claim 5 wherein:

A. said central hole and said dispersal plate each have diameters ofapproximately 3% inches;

B. said hollow cone of fuel measures 8095; and

C. said chimney has a diameter of approximately 12 inches and a lengthof approximately 24 inches.

7. The natural-draft space heater of claim 6 wherein 0.5 gallons of fueloil are ejected from said orifice per hour at psig fuel pressure andwherein a clean flame having a length of about 4 inches is obtainedafter ignition of said fuel oil.'

8. The natural-draft space heater of claim 6 wherein said orifice is al/64-inch orifice which ejects 0.5 gal lons of compressed gaseous fuelper hour at 0.5 psig fuel pressure and wherein a clean flame having alength of about 2 inches is obtained after ignition of said gaseousfuel.

9. The natural-draft space heater of claim 6 wherein said U-shaped plateis thin and has a square hole therethrough, and said fuel jet isattached to an elbow having a square cross-section into which a thinslot is milled, whereby said elbow is rotatably attachable to saidU-shaped plate and operates as a safety release means when said spaceheater is overturned.

10. The natural-draft space heater of claim 1 wherein a spacer meansthat spaces said fuel side sufficiently far from an underlining supportsurface that an adequate quantity of combustion air enters said centralhole, is formed by bending the comers of said base plate at right anglesto said fuel side and away from said flame side.

1. A natural-draft space heater, comprising: A. a flat base plate havinga flame side, a fuel side, and a central hole therethrough; B. a collarattached to said base plate in annular relationship to the said centralhole and on the flame side of the base plate, and acting as a chimneyalignment means; C. a removable chimney, having open ends, which isdisposed with one end perpendicularly adjacent to said flame side of thebase plate and aligned by saiD collar and in surrounding relationship tosaid central hole; said chimney being formed from a bendable metal platehaving backwardly bent edges which are engaged by a C-shaped slidefastener, said chimney being interchangeable end for end and removablefor storage; D. a substantially U-shaped fuel jet support means attachedto said base plate on the fuel side thereof; E. a fuel jet, having afuel inlet opening for pressurized fuels and an exit orifice capable ofejecting a hollow fuel cone, which is attached to said fuel jet supportmeans and disposed so that said fuel cone is in coaxial alignment withsaid central hole and does not contact said base plate; F. a dispersalplate support means; and G. a circular dispersal plate attached to saiddispersal plate support means which is aligned with and hassubstantially the same diameter as the diameter of said central hole insaid base plate and which is disposed in parallel relation to and spacedfrom the flame side of the base plate so that said dispersal plateintercepts said hollow fuel cone adjacent to said circular edge;whereby, in operation of said heater, the flame is attenuated outwardlyby the dispersal plate but without a substantial portion of the flamecontacting the side of the chimney, and with such substantially completecombustion occurring in the lower portion of the chimney that emissionof combustion particulates is substantially eliminated.
 2. Thenatural-draft space heater of claim 1 wherein said dispersal plate isdisposed in relation to said exit orifice so that said hollow fuel conecreates a ring of wet fuel adjacent to said circular edge beforeignition thereof.
 3. The natural-draft space heater of claim 2 whereinsaid ring of wet fuel extends 1/16 to 1/8 of an inch inwardly of saidcircular edge.
 4. The natural-draft space heater of claim 3 wherein saidexit orifice is spaced approximately one-fourth to 1/2 inch away fromsaid fuel side.
 5. The natural-draft space heater of claim 4 whereinsaid dispersal plate is spaced away from said flame side at a distanceapproximately equalling the diameter of said central hole.
 6. Thenatural-draft space heater of claim 5 wherein: A. said central hole andsaid dispersal plate each have diameters of approximately 3 1/2 inches;B. said hollow cone of fuel measures 80*-95*; and C. said chimney has adiameter of approximately 12 inches and a length of approximately 24inches.
 7. The natural-draft space heater of claim 6 wherein 0.5 gallonsof fuel oil are ejected from said orifice per hour at 70 psig fuelpressure and wherein a clean flame having a length of about 4 inches isobtained after ignition of said fuel oil.
 8. The natural-draft spaceheater of claim 6 wherein said orifice is a 1/64-inch orifice whichejects 0.5 gallons of compressed gaseous fuel per hour at 0.5 psig fuelpressure and wherein a clean flame having a length of about 2 inches isobtained after ignition of said gaseous fuel.
 9. The natural-draft spaceheater of claim 6 wherein said U-shaped plate is thin and has a squarehole therethrough, and said fuel jet is attached to an elbow having asquare cross-section into which a thin slot is milled, whereby saidelbow is rotatably attachable to said U-shaped plate and operates as asafety release means when said space heater is overturned.
 10. Thenatural-draft space heater of claim 1 wherein a spacer means that spacessaid fuel side sufficiently far from an underlining support surface thatan adequate quantity of combustion air enters said central hole, isformed by bending the corners of said base plate at right angles to saidfuel side and away from said flame side.